Hot Isostatic Pressing (HIP) is one of the most important manufacturing processes to improve the performance of powder metallurgy nickel-based superalloys produced by Laser Powder Bed Fusion (LPBF), which can effectively reduce the pores and cracks in the LPBF alloys. However, there are limited studies on the effects of tuning HIP parameters on the LPBF alloys microstructure and mechanical performance. In this paper, we systematically studied the effects of hot processes on the microstructural evolution and tensile properties of an LPBF prepared typical second generation of powder metallurgy (PM) nickel-based superalloy which was designated as FGH4096. The as-deposited alloy was HIP treated at sub-solvus, solvus, and super-solvus temperature, respectively, followed by an optimized heat treatment (HT). The effects of HIP temperature on the microstructures and mechanical properties of the LPBF alloys were studied by Optical Microscope (OM), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and Electron Backscattered Diffraction (EBSD). The results indicated that both HIP and HT processes led to recovery and recrystallization in the as-deposited alloy. During HIP, the increase of HIP temperature gradually eliminated the dendritic and equiaxed structures in the alloy while refined the grains along the long axis simultaneously. However, the columnar crystal morphology in the vertical section, together with straight grain boundaries, was still maintained during HIP. In all the HIPed alloys, the secondary γ′ precipitates were sparsely distributed, and due to the existence of continuous pressure, some grains with large strains remained. After HIP + HT, the dendritic and equiaxed structures basically disappeared. The grains with more curved grain boundaries tended to be equiaxed and irregularly shaped. Compared with other state alloys, the LPBF + HIP (solvus) + HT alloy has a more uniform and dense distribution of secondary γ′ precipitates, together with a chain distribution of block primary γ′ precipitates at the grain boundaries, which contributes mostly to the highest room and high-temperature tensile strengths. Moreover, the LPBF + HIP (solvus) + HT alloy has the lowest internal strain among the treated alloys, leading to the highest elongation.

热等静压（HIP）是提高由激光粉末床熔合（LPBF）生产的粉末冶金镍基高温合金性能的最重要的制造工艺之一，可有效减少LPBF合金中的气孔和裂纹。但是，关于调整HIP参数对LPBF合金的微观结构和力学性能的影响的研究有限。在本文中，我们系统地研究了热工艺对LPBF制备的典型第二代粉末冶金（PM）镍基高温合金（称为FGH4096）的LPBF的组织演变和拉伸性能的影响。沉积后的合金分别在亚固溶，固溶和超固溶温度下进行HIP处理，然后进行优化的热处理（HT）。通过光学显微镜（OM），扫描电子显微镜（SEM），透射电子显微镜（TEM）和电子背散射衍射（EBSD）研究了HIP温度对LPBF合金组织和力学性能的影响。结果表明，HIP和HT工艺均导致沉积态合金的恢复和重结晶。在HIP过程中，HIP温度的升高逐渐消除了合金中的树枝状和等轴结构，同时沿长轴同时细化了晶粒。然而，在HIP过程中，垂直截面的柱状晶体形态以及直的晶界仍然得以保持。在所有HIPed合金中，次生γ'沉淀物稀疏分布，并且由于存在连续压力，剩下一些大应变的谷物。HIP + HT后，树突和等轴结构基本消失。具有更弯曲的晶界的晶粒趋于等轴且形状不规则。与其他状态合金相比，LPBF + HIP（溶剂）+ HT合金具有更均匀和致密的二次γ'析出物分布，以及块状主要γ'析出物在晶界处的链状分布，这在很大程度上有助于最高的室温和高温拉伸强度。此外，在处理过的合金中，LPBF + HIP（固溶）+ HT合金具有最低的内部应变，从而导致最高的伸长率。与其他状态合金相比，LPBF + HIP（溶剂）+ HT合金具有更均匀和致密的二次γ'析出物分布，以及块状主要γ'析出物在晶界处的链状分布，这在很大程度上有助于最高的室温和高温拉伸强度。此外，在处理过的合金中，LPBF + HIP（固溶）+ HT合金具有最低的内部应变，从而导致最高的伸长率。与其他状态合金相比，LPBF + HIP（溶剂）+ HT合金具有更均匀和致密的二次γ'析出物分布，以及块状主要γ'析出物在晶界处的链状分布，这在很大程度上有助于最高的室温和高温拉伸强度。此外，在处理过的合金中，LPBF + HIP（固溶）+ HT合金具有最低的内部应变，从而导致最高的伸长率。